Mobile devices such as cellular telephones, smart phones, and tablets have become part of everyday life for millions of people. Users rely on their mobile devices to place calls, keep schedules, send e-mails and messages, capture images, and perform a variety of other tasks. These devices may contain sensitive, secure, and/or confidential information, such as financial information, private photographs and messages, and other data. Moreover, these mobile devices may soon replace credit cards, keys, and identification cards altogether, causing them to store even more sensitive and private information.